1. Field of the Invention
The present invention relates to a mobile tracking system, a camera and a photographing method.
2. Related Background Art
It is possible, in the prior technology, to track a mobile object by a single camera, utilizing an image processing technology. However, as it is difficult to continuously photograph a mobile object with a single camera over a wide range, multiple cameras are required for photographing a mobile object over a wide range. Mobile tracking systems using multiple cameras are classified into a centralized control type and an autonomic dispersed type. In the centralized control type, as the dispersed data are collectively managed, it is possible to recognize the status of the entire system. However, this type is unsuitable for a system of a large magnitude because of an increased burden on a server. Also it involves a risk that a failure in the server affects the entire system. On the other hand, an autonomic dispersed type, in which data processing is executed in each piece of equipment, imposes a limited burden on a network even in a large magnitude system. A mobile tracking system requiring cooperation of multiple-cameras has various advantages, such as flexibility in operation, and robustness by the integration of results of observation from various angles. It is thus rendered possible to realize various applied systems, such as a wide-range monitoring system or an ITS (intelligent transport system).
As an example, Japanese Patent Application Laid-open No. 2004-72628 discloses a mobile tracking system utilizing multiple-cameras, and a method therefor. A camera agent enters a moving image, photographed with a camera, by every frame into a processor, which analyzes a frame image, thereby extracting a person area in the image and a feature amount thereof. Then frames are matched on a time-axis by the extracted feature amount, thereby realizing extraction of a personal image and a feature amount thereof. When the camera agent detects a person, a tracking agent is generated. Multi-tracking agents constitute a group including a main agent and multi-sub agents, and the tracking agent functioning as the main agent summarizes the feature amount of the person, thereby achieving a cooperative operation.
However, in order to correlate a pixel position in the image of each camera with a coordinate system common to multiple-cameras (calibration of camera), one camera is installed in a fixed position and has a fixed view angle. Also since the view angles of the cameras have to overlap partially, a large number of cameras have to be employed for covering a wide range.